Musnad Ahmad 658:193

Waki' narrated to us, al-A'mash narrated to us, from Talhah ibn Musarrif, from 'Abd al-Rahman ibn 'Awsajah, from al-Bara' ibn 'Azib, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever grants a *maniha* (a gift for temporary use) of silver, or a *maniha* of milk, or guides someone along a path, it shall be for him like the equivalent of freeing a slave." And he said once: "Like freeing a slave."